I am not to good with #'s

[kbstenberg]

I am wanting to get my straight WW alloy to have about .4% copper added to it.
My intentions are to add Zink to contaminate my WW. So I can take the zink out of the alloy with the Copper Sulfate (sp) method of zink cleansing. But I am unsure of how much zink to add to the WW so my end outcome is only the .4% copper.
I would like to have about 50 lbs of lead with a copper additive.
Would I take 50 (the number of lbs lead) multiply by .4 (the quantity of copper wanted) = which would give me the quantity of zink to add
If some one can tell me how much Zink I would have to add to the WW. I would be greatly appreciated! Kevin

[Defcon-One]

Zinc, don't do it! There must be better/easier ways to add copper.

[bumpo628]

Rotometals makes a babbitt called "Super Tough Grade 3". It has 83-85% tin, 7.5-8.5% antimony, 7.5-8.5% copper and costs about $19 / lb
http://www.rotometals.com/product-p/alloy_super_tough_babbitt.htm

I plugged those numbers into my alloy calculator:
47.5 lbs of clip on WW + 2.5 lbs of babbitt = an alloy with @ 4.5% tin, @ 3% antimony, and 0.4% copper

A little high on tin, but that is one way to do it. Still not as high as Lyman #2 though.


To answer your math question, to get 0.4% zinc into 50 lbs of alloy you would add 0.2 lbs of zinc to 49.8 lbs of COWW.
0.2 lbs = 50 lbs x .004 (the .004 is 0.4% converted to decimal)
However, I agree with Defcon-One: I would find another way to do it.

[sqlbullet]

I think you could get to .4% copper with a MAP torch and a small steel measuring cup and a cast iron pot of HOT lead lead.

I would melt 13 oz of tin in the steel cup with a MAP torch and then melt/dissolve about 3 oz of copper. Once this was liquid I would add it the cast iron pot which had about 39 lbs of VERY HOT isotope alloy. I would flame and flux with motor oil until the mixture was liquid. I did not monitor temps so I can't speak to what they were.

That should yield a final alloy 93.5% lead, 3% antimony, 3% tin and .5% copper give or take a couple hundredths of a percent.

You should be able to use pure lead in place of the isotope alloy. That would yield 97.5% lead, 2% tin and .5% copper.

I did this a little over a year ago, but then embarked on a major remodel of my home which included tearing down my casting shop. As a result I have about 40 lbs of the isotope base alloy boxed up but have never cast a bullet with it. I do remember it was an enormous pain to do it this way, but easier I think than the zinc method you describe.